Len Ovens wrote: > On Wed, 3 Jun 2015, David Christensen wrote: > >> On 06/02/2015 06:32 AM, Glen MacArthur wrote: >>> ... I've received a few mic >>> shocks to the lips over the years when I used to run a vintage amp >>> without >>> a ground (it only had a ground lift toggle switch)... It didn't take me >>> long to upgrade the wiring to a fully grounded cord.. :).. >> >> I'm curious -- if an electric guitar amplifier has a two-conductor power >> supply cord (with hot and neutral conductors only) and a "ground lift" >> switch, what does the switch do? >> >> >> Can you provide an example make and model that has a schematic available >> on >> the web? For example: >> >> http://www.thevintagesound.com/ffg/ > > I don't know about ground switch, but some of them had a "hum" switch or > something similar... flipped the ac lines. Sometimes the "neutral" was > connected to chassis... which with no keying on the ac plug meant the > chassis might just as easy be hot. Nobody has done that for a long time > now. The idea was old and outdated 50 years ago. (probably before) > > -- > Len Ovens > www.ovenwerks.net > > _______________________________________________ > Linux-audio-user mailing list > Linux-audio-user@xxxxxxxxxxxxxxxxxxxx > http://lists.linuxaudio.org/listinfo/linux-audio-user > Len Yes that's what it was, however the toggle switch itself said 'Ground' on the back the amp chassis.. Both the bass player and I had vintage Traynor amps, he had a YBA-1 and I had a YGM4 Studio Mate, If you google the model numbers you can find the schematics, however a quick look didn't show me a schematic prior to 1973 but to my knowledge these amp models date back to the late 1960's. It appears that the 1973 schematics show a chassis grounded plug.. In any case both of these amplifiers had ungrounded 2-prong molded plugs and if the toggle was switched wrong with the wiring at whatever venue we were playing at we would get shocks off of the microphones...lol I heavily modified and sold mine to a nephew many years ago but Traynor actually re-issued both of these amp models in recent years (with proper electrical supplies). Had I known it was a classic... well hindsight is always 20/20... To this day I still keep a respectable distance from microphones when I sing... Glen _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
